feat(contracts) - add custom errors

[ctrlc03]

• change in contracts
• fix tests
• upgrade hardhat/etheres libraries
• remove jest and use mocha/chai for catching custom errors

fix #761
fix #774

[baumstern]

Just want to get a better grip on the benefits. I'm asking purely to learn:

• Could you shed some light on the gas fee savings with these custom errors (Is it less than $1, between $1-$10, or more than $10?)?
• I saw custom errors like error NotInit();—are these accompanied by custom messages too? I didn't spot any.
• What are the advantages of using mocha/chai over jest for this particular case?

[ctrlc03]

• shed some light on the gas fee savings with these custom errors (Is it less than $1, between $1-$10, or more than $10?)?

Just want to get a better grip on the benefits. I'm asking purely to learn:

• Could you shed some light on the gas fee savings with these custom errors (Is it less than $1, between $1-$10, or more than $10?)?
• I saw custom errors like error NotInit();—are these accompanied by custom messages too? I didn't spot any.
• What are the advantages of using mocha/chai over jest for this particular case?

1. this should explain in deeper details how custom errors work: https://soliditylang.org/blog/2021/04/21/custom-errors/. hard to put a price tag on the savings, they however are savings.
2. That is the error message - NotInit (the contract was not initialized already) -> can change to NotInitialized() if you think it's not clear enough.
3. • hardhat tests run using mocha not jest -> I have tried to make some changes to the tests, for instance running using two signers, however I was unsuccessful when using the code as it is now. I believe starting to run the tests directly with hardhat will allow us to do much more thorough tests, as well as simplify the code/scripts down the line -> the next step is to actually improve the tests and all the deploy scripts which look a bit rudimental to me.
   • custom errors need chai matchers

[baumstern]

It looks like the main problem this PR wants to address is 'Contracts inheriting the MACI contracts could fail to deploy due to hitting contract size limit,' as mentioned in #761. But we shouldn't compromise on the clarity of error messages. One middle-ground solution could be to use concise error codes in the contract and provide inline comments for additional context. Another approach would be to maintain an external error code table for comprehensive explanations, making it easier for debugging without affecting contract size.

[baumstern]

The term 'WrongPollOwner' is ambiguous and could imply various issues—whether the owner is not set, incorrectly set, or unauthorized. This lack of specificity contrasts with the original message.

[ctrlc03]

in Solidity if a value is not set it would be set as the default value -> in the address case it would be address(0). Now let's evaluate: address(0) != address(this) -> this would evaluate as false -> address zero (which is not set) is the wrong poll owner.
Given the contracts inherit the Ownable library, once a contract is deployed, the contract owner becomes the address deploying -> it could only be "not set" (which really is set to address(0)) if they were to renounce ownership -> hence stil incorrect owner.

[baumstern]

This table compares the deployed sizes and shows how much they have been reduced by introducing custom errors:

| Contract Name                       | Original Size (KB) | Improved Size (KB) | Reduction (KB)  |
|-------------------------------------|--------------------|--------------------|-----------------|
| AccQueueBinary0                     | 7.100              | 6.356              | -0.744          |
| AccQueueBinaryMaci                 | 7.100              | 6.356              | -0.744          |
| AccQueueQuinary0                   | 7.551              | 6.797              | -0.754          |
| AccQueueQuinaryBlankSl             | 7.551              | 6.797              | -0.754          |
| AccQueueQuinaryMaci                | 7.551              | 2.061              | -5.490          |
| Address                            | 0.086              | 0.084              | -0.002          |
| CommonUtilities                    | 0.063              | 0.062              | -0.001          |
| ConstantInitialVoiceCreditProxy    | 0.372              | 0.363              | -0.009          |
| DomainObjs                         | 2.110              | 0.061              | -2.049          |
| ERC20                              | 2.141              | 2.091              | -0.050          |
| ERC721                             | 4.575              | 4.468              | -0.107          |
| FreeForAllGatekeeper               | 0.425              | 0.415              | -0.010          |
| Hasher                             | 1.820              | 1.777              | -0.043          |
| HasherBenchmarks                   | 1.926              | 1.881              | -0.045          |
| IMessage                           | 0.063              | 0.062              | -0.001          |
| IPubKey                            | 0.063              | 0.062              | -0.001          |
| MACI                               | 7.870              | 7.103              | -0.767          |
| Math                               | 0.086              | 0.084              | -0.002          |
| MessageProcessor                   | 7.831              | 7.465              | -0.366          |
| MockVerifier                       | 0.966              | 0.938              | -0.028          |
| Pairing                            | 0.086              | 0.084              | -0.002          |
| Params                             | 0.063              | 0.062              | -0.001          |
| PoL1                               | 7.679              | 7.002              | -0.677          |
| PollDeploymentParams               | 0.063              | 0.062             | -0.001         |
| PoLFactory                         | 21.637             | 19.802             | -1.835          |
| PoseidonT3                         | 0.281              | 0.274              | -0.007          |
| PoseidonT4                         | 0.279              | 0.272              | -0.007          |
| PoseidonT5                         | 0.279              | 0.272              | -0.007          |
| PoseidonT6                         | 0.279              | 0.272              | -0.007          |
| SafeERC20                          | 0.086              | 0.084              | -0.002          |
| SignUpToken                        | 5.435              | 5.308              | -0.127          |
| SignUpTokenGatekeeper              | 1.610              | 1.294              | -0.316          |
| SnarkCommon                        | 0.063              | 0.062              | -0.001          |
| SnarkConstants                     | 0.063              | 0.062              | -0.001          |
| Strings                            | 0.086              | 0.084              | -0.002          |
| Subsidy                            | 6.460              | 6.211              | -0.249          |
| Tally                              | 6.286              | 6.001              | -0.285          |
| TopupCredit                        | 3.361              | 3.282              | -0.079          |
| Utilities                          | 2.885              | 2.817              | -0.068          |
| Verifier                           | 3.743              | 3.655              | -0.088          |
| VkRegistry                         | 6.506              | 6.005              | -0.501          |

[baumstern]

Thank you for taking the time to go through the comments and making those adjustments. LGTM!